The present invention is directed to radio automatic gain control circuits (AGC), and more particularly to digital AGC circuits.
Many conventional narrow band zero intermediate frequency (ZIF) receivers have slow AGC loop settling times, such as on the order of 6 to 10 milliseconds (msec.), and dynamic ranges that are too narrow, e. g., 85 decibels (dB). These characteristics lead to less than desirable performance in the fading conditions found in mobile and portable radio communication systems, such as paging, personal communication systems, and cellular communication systems. Furthermore, inexact gain control by prior art AGC""s increases the difficulty of reducing DC offset, which reduces signaling performance. What is needed is a low cost, low power AGC that is fast, has a dynamic range in excess of 110 dB and provides more exact gain control.